@girish Thanks for the quick reply, 👍.
In case anyone else needs this on 22.04, I followed these steps and was able to get the system to boot with full disk encrypted drive with the private key coming from the tpm and no password needing to be typed.
I don't think this uses the same libraries as the new option in 23.10 so I expect that when 24.04 comes out I will do a fresh OS install to use the better supported FDE TPM integration from that version going forward but as a stop gap I am happy with this for now.